
#include <iostream>
#include <vector>
#include <cstdio>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <functional>


int main()
{
    pid_t id = fork();
    if(id == 0)
    {
        // child
        while(true)
        {
            printf("我是子进程, pid : %d\n", getpid());
            sleep(1);
        }
        exit(0);
    }

    // father
    while(true)
    {
        sleep(1);
        pid_t rid = waitpid(id, nullptr, WNOHANG);
        if(rid > 0)
        {
            printf("等待子进程%d 成功\n", rid);
            break;
        }
        else if(rid < 0)
        {
            printf("等待子进程失败\n");
            break;
        }
        else
        {
            printf("子进程尚未退出\n");
        }
    }

}
